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HomeMy WebLinkAbout8.2 TJKM Report 87-1 CITY OF DUBLIN AGENDA STATEMENT City Council Meeting Date: February 8, 1988 SUBJECT: 87-1 Informational Report on Traffic Signal Interconnect EXHIBITS ATTACHED: Report from TJKM A representative fr0m TJKMwill 5e available at the meeting to answer questions. RECOMMENDATION: ~eceive Report FINANCIAL STATEMENT: None DESCRIPTION: The City's Traffic Signal Interconnect is now operational at all intersections on Dublin Boulevard with the exception of San Ramon Road and Dougherty Road. TJKM observed the field conditions and adjusted the timing on a daily basis for several weeks and arrived at the following patterns: Pattern Days Time Cycle Length Monday through Friday 7:30 a.m. 8:45 a.m. 95 seconds Midday Monday through Friday 11:45 a.m - 1:15 p.m. 130 seconds P.M. Monday through Friday 4:00 p.m. - 6:00 p.m. 120 seconds Shopping Saturday & Sunday 11:00 a.m. - 6:00 p.m. 120 seconds At other times, the signals are not coordinated but operate on demand. On the coordinated system, the same cycle length is required for all intersections so that their timing with each other is maintained. There is a guaranteed green time for Dublin Blvd. which prevents cross streets and left turn phases from being served during that time. During the hours the system is operating, signals will have longer green times on Dublin Blvd. and longer red times for cross streets and left turn phases. The purpose of the system is to improve traffic flow along the more heavily traveled street, Dublin Blvd., the end result being greater fuel efficiency. During the times of day that the system is on free operation, each intersection operates on its own according to traffic demand. At this time, the Dougherty Road intersection is not included in the system because of the excessively long cycle lengths required. The FETSIM project has concluded that the system operates more efficiently if this intersection is not included in the progression. Another contributory factor is the 1-580 overcrossing construction, which causes additional congestion. The San Ramon Road intersection will be included in the progression as soon as the City receives a logic unit for the controller which will permit an exclusive pedestrian phase to cross Dublin Boulevard on the east leg of the intersection. Staff initiated the exclusive pedestrian phase in order to help insure safety for pedestrians crossing the double right-turn lanes. The logic unit has been ordered, with the anticipated delivery date in March. Items identified in TJKM's report as "Future Activities" may be undertaken in successive phases of the interconnect project. ITEM NO.~ COPIES TO: TJKM MEMORANDUM 4637 Chabot Drive, Suite 214 Pleasanton Ca. 94566 (415)463-0611 DATE: TO: FROM: SUBJECT: December 23, 1987 Lee Thompson, City of Dublin Chris Kinzel Status of Dublin Boulevard Interconnect System Status On December 7, 1987, coordination was implemented on Dublin Boulevard using the Traconex system and timing provided by the FETSIM project. There are three weekday patterns and a weekend pattern: Coordination Patterns Cycle Pattern Days Time Length Monday thru Friday 7:30 a.m. - 8:45 a.m. 95 seconds Ivlidday Monday thru Friday II:45 a.m. - 1:15 p.m. 130 seconds Monday thru Friday 4:00 p.m. - 6:00 p.m. 120 seconds Shopping Saturday and Sunday 11:00 a.m. - 6:00 p.m. 120 seconds At all other times the signals are running free (not coordinated). With the exception of the lack of coordination on Dublin Boulevard between San Ramon Road and Regional Street, the coordination along Dublin Boulevard has been working well. John Gildea of our office has been observing the field conditions and adjusting the timing on a daily basis since coordination was implemented. Although the coordination timing has functioned well with the normal daily traffic, it appears that the very heavy traffic of these days immediately before Christmas is overloading the system. However, we believe that the coordination timing is handling the Christmas rush better than the uncoordinated timing we have had in the past. We will continue to observe the traffic and adjust the timing as required. Description of Coordination The method of coordination used by the Traconex system is called background cycle coordination. All coordinated intersections are forced to use the same cycle length so that each intersection can maintain its timing in relationship to the other intersections. PLEASANTON · SACRAMENTO · FRESNO · CONCORD Mr. Lee Thompson -2- December 23, 1987 The start of the green time on Dublin Boulevard is set at each intersection to provide progressive traffic flow along Dublin Boulevard. The system provides a guaranteed green time for Dublin Boulevard and prevents cross street and left turn phases from being served during this time. Thus, during the hours of coordinated operation, the signals will have longer green times on Dublin Boulevard and longer red times on the cross streets and the left turn phases. During coordination you can drive on Dublin Boulevard from Regional Street to Dublin Court with very few, if any stops for red signals. You will probably notice longer than normal queues of traffic waiting for side street phases or left-turn phases to turn green. In contrast, during free operation, each intersection signal is operating independently and responding to traffic demand at the intersection. If you drive the length of Dublin Boulevard you may have to stop at almost every signal, depending on the side street and left turn traffic. However, the waiting queues on the side street and left turn phases will be somewhat shorter because the signal responds more readily to these demands during free operation. Problem Intersections Two intersections are not coordinated at present: Dublin Boulevard/Dougherty Road and Dublin Boulevard/San Ramon Road. Dublin Boulevard/Dougherty Road requires excessively long cycle lengths. The conclusion of the FETSIM project is that it is more efficient to operate this intersection independent of the Dublin Boulevard system. Also, the current construction of the 1-580/Dougherty Road freeway overpass is causing some congestion and limiting the capacity of the Dublin Boulevard/Dougherty Road intersection. Dublin Boulevard/San Ramon Road can not be coordinated at present because of the unusual phasing which provides an exclusive pedestrian phase to cross the double right-turn lanes of northbound to eastbound traffic. After Traconex modifies the controller cabinet by installing a logic unit, this intersection will be added to the coordination patterns. As of December 16, 1987, Traconex had not received an order from the City for this modification although they had received the technical information. This is a crucial element to coordinate both Dublin Boulevard and San Ramon Road. Future Activities To improve and expand the operation of the system, the following activities should be undertaken: Complete the installation of the logic unit for Dublin Boulevard/San Ramon Road. This will allow this intersection to be added to the coordinated system. Manually adjust the timing based on field observation to improve the operation of the system. 3. Use the traffic counting features of the system to adjust and possibly expand the hours of coordinated operation. Implement traffic responsive operation, based on traffic volume studies. Traffic responsive operation would allow automatic selection of coordinated operation based on current traffic counts rather than by time of day. Mr. Lee Thompson -3- December 23, 1987 Complc~ the FETSIM project by doing the 'after' portion of the speed and delay study and preparing the final report. The 'after' study was done during the week of December 14, 1987 and the final report is currently being written by TJKM. Study the possibility of changing thc phase sequence at selected intersections to improve the operation. This is a capability of the system we are not currently using. Obtain new counts and study the intersection of Dublin Boulevard/Dougherty Road to determine whether there is any way to coordinate this intersection, at least during certain times of day. 8. Implement coordination at the intersections of San Ramon Road/Amador Valley Boulevard and San Ramon Road/$ilvergate Drive. 9. Install interconnect cable and implement coordination at additional intersections throughout Dublin. For additional information, please contact John Gildea of our office. nlc cc: Richard Ambrose 157-001